Evaluation of carnitine nutritional status in full-term newborn infants

Carnitine supplements may be advisable not only in premature but also in ar tificially-fed full-term babies. The acyl-carnitine/free carnitine (AC/FC) and FC/total camitine (FC/TC) ratios have been considered markers of "carni tine insufficiency" and "carnitine deficiency", respectively. Values of AC/ FC > 0.40 are considered abnormal and mean that FC has a low bioavailabilit y to the cells and so reflects a "carnitine insufficiency". Values of FC/TC < 0.7 indicate "carnitine deficiency". We analyze the validity of such rat ios and the limits for them in three groups of full-term neonates (n = 66): 22 breast-fed (BF), 22 with formula (F); and 22 fed with carnitine-supplem ented formula. Several studies have shown the need to give supplements of c arnitine to the neonate because of its "essentiality", but no one has demon strated the adequate dosages. We therefore propose to establish new limit l evels for these ratios to control carnitine nutritional status in neonates, based on the control of percentile ranges for normal BF infants (in this s tudy: 97th percentile of AC/FC > 0.83; 3rd percentile of FC/TC < 0.54) and on evaluating the needs of neonates and dosages required to supplement F. T he supplement of 2.2 mg of L-carnitine/100 ml in the cow's milk formula use d in the present study produces a similar biochemical pattern of plasma car nitine and ACs to that observed in BF infants, together with a lower risk o f developing "carnitine deficiency" or "carnitine insufficiency" than those babies fed with nonenriched F. Considering that human milk is the best sou rce of nutrition for full-term infants, the limit established for AC/FC and FC/TC ratios at other ages of life seems to be "inadequate" for neonates. (C) 1998 Elsevier Science ireland Ltd. All rights reserved.